blob: cf2511c33905751bb6ed866bf6bba9b1fb8330f3 [file] [log] [blame]
Alexei Starovoitov65d472f2016-05-05 19:49:14 -07001/* Copyright (c) 2016 Facebook
2 *
3 * This program is free software; you can redistribute it and/or
4 * modify it under the terms of version 2 of the GNU General Public
5 * License as published by the Free Software Foundation.
6 */
7#include <linux/ip.h>
8#include <linux/ipv6.h>
9#include <linux/in.h>
10#include <linux/tcp.h>
11#include <linux/udp.h>
12#include <uapi/linux/bpf.h>
13#include <net/ip.h>
14#include "bpf_helpers.h"
15
16#define DEFAULT_PKTGEN_UDP_PORT 9
17
18/* copy of 'struct ethhdr' without __packed */
19struct eth_hdr {
20 unsigned char h_dest[ETH_ALEN];
21 unsigned char h_source[ETH_ALEN];
22 unsigned short h_proto;
23};
24
25SEC("simple")
26int handle_ingress(struct __sk_buff *skb)
27{
28 void *data = (void *)(long)skb->data;
29 struct eth_hdr *eth = data;
30 struct iphdr *iph = data + sizeof(*eth);
31 struct udphdr *udp = data + sizeof(*eth) + sizeof(*iph);
32 void *data_end = (void *)(long)skb->data_end;
33
34 /* single length check */
35 if (data + sizeof(*eth) + sizeof(*iph) + sizeof(*udp) > data_end)
36 return 0;
37
38 if (eth->h_proto != htons(ETH_P_IP))
39 return 0;
40 if (iph->protocol != IPPROTO_UDP || iph->ihl != 5)
41 return 0;
42 if (ip_is_fragment(iph))
43 return 0;
44 if (udp->dest == htons(DEFAULT_PKTGEN_UDP_PORT))
45 return TC_ACT_SHOT;
46 return 0;
47}
48char _license[] SEC("license") = "GPL";